Compounds having polymerizable groups (polymerizable compounds) are used for various optical materials. For example, by aligning a polymerizable composition containing a polymerizable compound into a liquid crystal state and then polymerizing the resulting polymerizable composition, a polymer with uniform alignment can be produced. Such a polymer can be used for polarizing plates, retardation plates, etc. necessary for displays. In many cases, polymerizable compositions containing two or more polymerizable compounds are used in order to meet the required optical properties, polymerization rate, solubility, melting point, glass transition temperature, transparency of polymers, mechanical strength, surface hardness, heat resistance, and light fastness. It is necessary for the polymerizable compounds used to provide good physical properties to the polymerizable compositions without adversely affecting other characteristics.
To improve the viewing angle of liquid crystal displays, it is necessary for retardation films to show birefringence with weak or reverse wavelength dispersion. Various polymerizable liquid crystal compounds with reverse or weak wavelength dispersion have been developed as the materials of these retardation films. When these polymerizable compounds are added to polymerizable compositions, crystals are precipitated, so that the storage stability of the polymerizable compositions is insufficient (PTL 1). Another problem with these polymerizable compounds is that when the polymerizable compositions are applied to substrates and polymerized, unevenness easily occurs (PTL 1 to PTL 3). When an uneven film is used for, for example, a display, a problem arises in that the quality of the display product deteriorates significantly because of unevenness in display brightness or unnatural color tone. There is therefore a need for the development of a polymerizable liquid crystal compound with reverse or weak wavelength dispersion that can solve the above problems. To solve the unevenness problem, specific surfactants are generally added to polymerizable liquid crystal compound compositions (PTL 2 to PTL 5). Another problem is that, when a polymerizable composition is applied to substrates and polymerized and the substrates are stacked and brought into contact with each other, the surfactant present on the coated surfaces is offset onto the substrates, causing poor appearance. An important technique to solve the coating unevenness problem and the offset problem simultaneously is to select an optimal surfactant.